Aircraft structure



Feb. 4,- 1941. A. P. DE SEVERSKY 2,230,614

l `AIRCRAFT STRUCTURE Filed oct-27. 19157 2 sheets-sheet 1 lNyEN'roR f ALEXANDER D. da'sEvER'SKY',

l Hls ATTORNEY. j

AIRCRAFT STRUCTURE INVENTOR:

ALExANDl-:R e de sEvERsKY; l

B g Y HIS ATTQRNF'.' 7

Patented Feb. "4, 1941 AIRCRAFT PATENT ori-*ICE STRUCTURE Alexander P. de Seversky, Asharoken Beach,

N. Y., assigner to Seversky Aircraft Corporation,

a corporation of Delaware Application october 27, 1937, serial No. 171,215

8 Claims.

The present invention relates to airplanes and its chief object is to provide a construction forming a part of the fuselage structure such thatif, upon landing, the craft noses over and lands upon its back, a crushing of the top of the fuselage, or injury to the pilot and passengers will be prevented.

Another object is to provide a-crash protector the total height of which above the cockpit can be automatically reduced to the minimum during night, in order that lunnecessary drag, etc. may be avoided and yet wherein the height may be sufliciently increased, when landing or taking off, to provide the requisite distance of the protecting means above the pilots head.

Another object is to provide a crash protector which can be raised by the lowering of the landing gear, in one simultaneous operation.-

A further object is to provide a crash protector which will noty only prevent structural damage to the airplane but will directly absorb nosing-over shocks and minimize the stress upon the fuselage and jars to the pilot and passengers.

The invention also aims to provide a crash protector of this improved nature which will nonetheless obscure the iield of vision of a pilot or passenger in an after cockpit by only the minimum amount.

For the purposes of exemplification, the ina multiple cockpit airplane with the crash protector built in rigidly with one or more transverse members, ,such as the bulkheads between two cockpits. It will bel understood, however, that this particular embodiment is illustrative -merely and that the invention may be embodied in any construction within th'e scope of the subjoined claims. j

The nature and objects .of the invention will 40 be better understood from a description of a particular embodiment, for the purpose of which description reference will be had to the accompanying drawings forming a part hereof and in which- Figure 1 isa broken-away side view, partly in section, showing a crash protector construction in accordance with the invention an aeroplane fuselage,

Figure 2 is a transverse sectional view taken on the'line 2,-2 of Fig. 1,

Figureis a sectional view taken' on the line 3-3 of Fig. 1, and

Figure 4 is a diagrammatic side tially broken away.

elevation, parof a modication.

vention will be herein described as embodied inembodied in In the embaiment mustrated in Figures 1 3,

inclusive, the fuselage of an airplane is constructed with certain` members projectible, on occasion, a distance above the top, or uppermost portion, of the fuselage, including the canopies or cabin-tops, and suicient to support the static 5 Weight and absorb the impact energy of the airplane, when same inverts and lands on its back, as in an outside, vertical ground-loop (due to nc' singover).` 'Ihereby the chances 'of A,damage to the superstructure and fuselage, and to the occupants, is reduced to the minimum.

More specically, these protective means comprise a member 5 for directly engaging the ground, and movable vertically by the impact of a nose-over-landing, in a vertical cylinder I6. The strut 5 is also positively adjustable, automatically, into the extended position shown`in full lines in Fig. 1, when preparing for landing and positively retractible, automatically, into the retracted position shown in dotted lines in Fig 1, in order not to diminish or interfere with, the aerodynamic characteristics of the fuselage, etc. In the construction shown, the strut-member 5 is mounted in the cylinder` I6 in such manner as to-be vertically reciprocable therein, the cylinder I6 being in turn mounted for vertical reciprocation in a cylinder 6. The cylinder 6 forms a rigid stationary part of a bulkhead 'I located rearwardly of the forward cockpit, and is braced by longitudinally-extending web members I0 lying. at the sides of the fuselage and including a truss Il. Both the web and the truss are secured to another bulkhead l2, of the fuselage, farther aft. Any stresses arising inthe strutsystem arev therefore satisfactorily distributed throughout the fuselage-framing, `and thus nosing-over forces are taken oil' the portions of the fuselage that'lie closely adjacent the cockpits. Thereby the superstructure, such as canopies, and the fuselage structure, such as bulkheads, at the cockpits especially, are effectively protected against. crushing in the event the craft noses over on landing, and, if the occupants are, as is usual, strapped in on landing, they are also protected from sudden contact with hard objects.

The structure cooperating with the strutv 5 includes not only means for-taking the weight and impact of the A airplane and for automatically projecting the Nstrut to the desired protective height on landing'and retractingA it, out of the air stream during night, but also incorporates means for absorbing shocks to the end that the occupants will not even be jarred if the plane lands on its back.

The structure and arrangement shown in Fig-'- ures 1-3 inclusive. provides all these features, and includes a hollow interior in the strut 5, with an aperture I5 in the bottom end of the strut. The strut 5, as mentioned, is vertically movable up and down, in the cylinder I6, and

the topmost end of the strut is constructed ,with

a closed hemispherlcal rubber pneumatic cap 20, which dissipates the initial sharp impact-energy 'when the strut 5 first contacts the ground, and

reduces the immediately following stress arising in the strut itself. The cylinder I5 ts within, and is similarly vertically movable in, the cylinder 6. The cylinder I6 thus constitutes an intermediate plunger for the parts 5 and 6. Plunger I6 is constructed with a substantially centrally .located horizontal partition I1, defining a chamber I8 in the plunger. Chamber I8 is filled with oil to such an extent that it rises in member 5 suiilciently to always stand at a level somewhat above the bottom wall of strut 5, leaving quite a large chamber, filled with air, above the oillevel in strut 5.

A valve I9 is provided in the cylinder IB, and it has a head somewhat larger than the rest of it. Suitable packing is provided at 2I between the strut 5 and the plunger I6, and at 22 between'the plunger I8 and cylinder 8.

When the airplane noses over and lands on its back, if the strut 5 is protruded at all above the superstructure of the airplane, the immediate impact energy of the outside ground loop will be entirely absorbed by the freturn, upward, forcing of the oil through the quite restricted aperture at I5, and by compressing the air in the upper part of strut 5 and the air in cap 20, the strut moving down in cylinder I8, the cylinder I6 remaining stationary in cylinder 5. If desired, however, theprotector-structure can be employed without this particular oil-valve shockabsorber arrangement.

'I'he crash-protector is extended into its uppermost position by forcing air under pressure into the upper part of the hollow strut 5, through an aperture 251 therein, to raise strut 5 in cylinder I8, and by simultaneously or subsequently forcing oil into cylinder 5 tol raise plunger I6 in cylinder 6. For raising strut 5, an air pump 24 is connected by a flexible air hose 25 to the air inlet 251 in strut 5, and as air is pumped into the hollow, the strut rises relatively to plunger I 6, opening the aperture at I5, by this action forcing `the oil level in strut 5 through aperture I5 into plunger I6. For raising plunger I6, oil is forced into .the cylinder 6 by an oil pump diagrammatically indicated `at 26, through a flow-and-return pipe 21.

In adjusting the device for landing or for ilying, oil is pumped to and from the cylinder 6 from an oil tank 28 through the single line 21'. The pumping of the oil from the cylinder 6 will directly and positively retract the plunger I8 in the cylinder 6 and render it unnecessary to provide any arrangement for forcing oil into the top of cylinder 5 in order to force plunger I5 downwardly. Pumping air from the plunger 5 through the aperture 251 and flow and return line 25 will ordinarily be sufcient to retract the strut-5 into the position shown in dotted lines in Fig. 1, but, if desired, more positive control may be obtained by pumping air or oil into the top ofthe plunger I6, as through an aperture 291 and .a piping line, not shown. A port 29 is preferably connected to the oil pump by suitable piping in order to give a positive oil pressure on the lower end of plunger I8 for positively retracting plunger I6 in conjunction with the hydraulic retraction of the landing gear, if such type of retraction bel employed. In such case, the retracting oil-line system is connected to port 28 and to lowering line 5 21, thus affording simple meansv of connecting the retractable landing gear and the retractable crash protector. If desired, in order .to more positively lower the strut 5 into .the position shown in dotted lines in- Fig. 1, an additional l0 airline, such as that ,shown at 50 in Fig. 1 for forcing air under pressure into the spac between 5 and '|6, may be provided, inwhich case a twoway air valve, not shown', is incorporated in pump 24. By these means, the air in cylinder 5, can, i5 if desired, be exhausted into the atmosphere, while the air is being forced into the space bctween the strut 5 and the plunger I8. Then, in landing,the airline 25 is closed off by the pilots operating a valve, not shown, in the air pump 24, 20

so that the extra air pressure generated by the impact will not bring unbalanced loads onto the air pump.

Inasmuch as it is contemplated to retract and project the strut 5 at the same time that the 25 landing gear is retracted and lowered, if a retractable landing gear is used, the landing gear and strut may conveniently be operated for simultaneous retraction or extension by the same source of power, such as a motor or hand crank. 30 In Fig, 1 there is diagrammatically indicated a retractable landing gear whereby the wheel 30- carried by the shock absorber strut 3| is retracted by a link 32 through a screw and nutmechanism 33, 3l. The screw is shown diagrammatically as 35 rotated by shaft 35 through bevel gears36 and connecting gearing. The shaft V35 is driven from a suitable hand crank-31 or a motor. For the purposes of illustration the pump 26 for pumping oil to and from the cylinder 5 and the air pump 40 24 for pumping air to the hollow strut 5 are diagrammatically shown as connected to be operated by the hand crank 31 and shaft 35.

It is contemplated that the construction of the crash protector shall obstruct as little as possible 45 the forward View of the pilot or passenger or observer in the cockpit to the rear of the crash protector or the rearward view of lthe occupant of the front cockpit. The crash protector of the present invention is adapted eminently to ac- 50 complish this, and is made as narrow as feasible at .the height ot the line of vision above the top of the fuselage, and in the construction shown the width of this structure is less than, or not substantially greater than, the width of the head 55 and neck of the pilot. The pilot, therefore, when turning to look backward may easily move his head to one lside or the other of thefprotector. and the passenger in the rear cockpit when look ing forward may easily get a clear view ahead. 60

It is also contemplated thatthe construction.

shown can be applied to opencockpit planes, inv

which case the construction will be carefully streamlined, as for example by vproviding a streamline fairing, and also that it will be applied such that the struty` may be projected up -also y when the cockpit is completely closed and the forward cockpit cover is in closed position. Such 'I5 an arrangement isshown in Fig. 1 and includes It is contemplated by the present invention that the arrangements for projecting andretracting the crash protector be variously modified, and mechanical means may be arranged for projecting or retracting the crash protector and the retractable landing gear preferably simultaneously, and the operating means for both may b e hydraulic, mechanical, electrical', pneumatic, or any desired combination of these. All the devices, also, may be operated either by hand or by a sultable motor. Furthermore, the operating mechanism can be inter-connected with any of the controls in the cockpit, such as the throttle, the tail wheel projecting device, or other controls instead of the landing gear projecting control, if desired.

In the formshown in Fig. 4, there is provided a crash protector embodying the present principles, which is operated non-hydraulically, being operatively connected to the non-hydraulically Voperated landing-wheels retracting mechanism.

'Ihe construction shown comprises a vertical cross-head or guide 52, located just aft of 'the' pilot-and suitably rigidly mounted and braced, as by members 53 and having a groove 54 in which a. land 55 cna slat or post-member 56 is vertically reciprocable. In the illustrative embodiment, the means for reciprocating the slat comprise a reversible screw-rod 51, threaded into the slat and carrying a bevel-gear 58 rigidly on its lower end. A meshing bevel-gear 59 is rigidly mounted on a stub-shaft in the guide 52, and the shaft isadapted to bedriven from the wheel-retractingmechanism 60 by means of a sprocket-wheel 5|, a sprocket-chain 62, and another sprocket-Wheel 63. Thus, when the pilot, in preparing to land, sets the wheel-retracting mechanism in operation, the slat 5S is automatically protruded upwardly, pushing open the spring hinged-plate 5|, until the slat extends the minimum distance above the pilots head,requisite for his safety. When, upon taking-olf, the pilot sets the wheel-retractingmechanism in operation, the slat is automatically retracted into the housing and the spring-loadedflap closes the aperture in the canopy, thus obthe slat and ap left protruded in flight.

It is contemplated that the strength of the crash-protector structure be such as to either rigidly resist the impact and static forces of Aan overturn,without yielding at all, or be such as to intentionally yield and crush to such an extent as to absorb this energy, in either case relieving the fuselage etc. of all dangerous-forces.

It is to be observed that, among the other advantages owing from the construction of the present invention, the canopy, cabin, or other superstructure can be made quite substantially lower than is usual, in order to provide more nearly perfect streamlining, etc. of the fuselage, yet a clearance between the top of the pilots head viating speed losses, etc. that would arise wereV and the most protuberant point on the upper lside of the airplane of at least the amount4 .for projecting said shock 3 flap for streamlining said opening and means to,- project said member upward wlth reference to thev fuselage to a position to support the air plane when the aircraft inverts against a, landing area.

2. In an airplane, a fuselage, a canopy' and means projectible above the canopy to support the weight and impact of the, fuselage when it inverts against a landing area, said means including a hydraulic shock absorber, said hydraulic shock-absorber being mounted concentrically in said projectible means, and means for projecting said shock-absorber independently of the said projectible means. A

3. In an airplane, a fuselage having a crash protector comprising a guide member rigidly secured in the fuselage, a strut movable in said guide to project above the top of the airplane, means connected to. said strut to move the same vertically in said guide, a retractable landing gear, means for projecting and retracting the same, and a common actuating means connected to contemporaneously actuate both the said crash protector and the retractable landing gear.

4. In an airplane having va fuselage and a retractable landing gear, a crash protector comprising a cylinder mounted in the fuselage, a plunger member movable in said cylinder, a shock absorber strut movable in the plunger to project above the fuselage and formingtherewith a hydraulic shock absorber, said' strut having a pneumatic shock-absorber on its lupper end to absorb minor shocks before the hydraulic shock-absorber comes into action and common means to project said landing gear and to force said plunger upward in the cylinder and independently operable to project the shock absorber strut upward in the plunger to project the. latter above the fuselage. 5. In an airplane, a fuselage having a.- crash protector, comprising a guiding-frame mounted rests upon said member and adapted tobe retracted out of the windstream when not in use, a liquid container carrying the projectible member therein, another member mounted in the first said member, a reservoir for-liquid, a pump connected to the reservoir, a conduit from the reservoir -to the bottom of the liquid container, a conduit from adjacent the top of said container to the reservoir, an air pump, a conduit therefrom to the firstmentioned member, a conduit from the member .mounted in said first-mentioned member to the air pump, said conduit having a ven't therein, and a single controlfor operating both said `pumps. 1 7. In an airplane, a fuselage and a canopy, a crash strut projectible above the canopy to support the weight and impact of the fuselage when it inverts against a landingl area, means for' extending an'd retracting said crash strut, said strut including a hydraulic shock absorber, saidhydraulic shock absorber being mounted concentrically in said projectible crash strut, and means absorber independently of the said crash strut.

8. In an airplane having a fuselage, a retractable landing gear mounted below the fuselage, I

means for extending and retracting said landing gear, a crash'protector mounted above the fuselage, means for extending and retracting said crash protector into and out of the slipstream around the fuselage, said crash protector in its extended position being capable o! breaking the impact and supporting the weight of the airplane should the latter invert in taking of! or landing, and common control means for simultaneously actuating the extending and retracting means of both the landing gear and crash protector.

ALEXANDER P. DE SEV'ERSKY. 

